A medical instrument of this kind is known from DE 93 02 650 U1.
The known medical instrument is designed in the form of medical forceps. A jaw head is arranged at the distal end of an elongate rigid shaft and is pivotable out from the longitudinal axis of the shaft. The jaw head has a rigid jaw part and a pivotable jaw part.
To pivot the jaw head, the latter is connected to a first actuation element in the form of a wire, which is guided all the way through the shaft to the proximal end. There, the wire is connected to a movable grip part of a scissor-like handle. This movable grip part represents a control element by which this wire can be moved axially to and fro in the shaft in order to pivot the jaw head. The design is such that, in a first range of movement of the grip element, both jaw parts are pivoted together, i.e. the entire jaw head is pivoted. In a second range of movement following on from the first one, the movable jaw part can be moved relative to the stationary jaw part, i.e. can be opened and closed. For this purpose, a second actuation element in the form of a further wire is present, which is connected at the distal end to the pivotable jaw part and connected at the proximal end to the pivotable grip element. The two wires extend alongside each other in the shaft.
Instruments of this kind are used, for example, in procedures in the maxillary sinus, in order to remove a section of tissue, for example a cyst or cartilage. For insertion, the distal end can be pushed into the nasal opening and introduced into the maxillary sinus through an aperture, a so-called window, provided in the nasal wall. The pivotability of the jaw head means that the latter can initially be oriented in a relatively rectilinear manner with respect to the shaft during insertion into the nasal cavity, and can be pivoted, with the jaw parts still closed, only upon insertion into the maxillary sinus. In this way, the jaw head can be brought to places lying to one side in relation to the direction of insertion through the nasal opening. The jaw parts are then opened and placed on the tissue to be separated, and a piece of tissue is separated by closure of the jaw parts.
If the tissue is cartilage, considerable forces have to be applied in order to separate a section of cartilage.
These are relatively slender medical instruments which, on the one hand, are intended to permit the greatest possible number of degrees of freedom of orientation of the jaw head and of the jaw parts with respect to the orientation of the shaft. On the other hand, the aim is to allow considerable forces to be transmitted despite the slender design.
In the medical forceps mentioned at the outset, the two wires of the actuation elements are arranged alongside each other in the shaft and lie spaced apart from each other and so take up quite a lot of space. A further disadvantage is that, in a first range of movement of a control element, the jaw head can only be pivoted, and it is only possible for the jaw parts to be opened and closed after this pivoting movement has been performed.
From U.S. Pat. No. 8,419,720 B1 a medical instrument is known whose outer rod has an articulated section at its distal end. For controlling the articulation a hollow actuation rod is disposed within the outer rod. The actuation rod is connected to a tension element within the articulation section of the outer rod. The actuation rod causes the articulated section to bend when tension is applied.
An attachment rod is inserted into the actuation rod. The attachment rod supports a jaw head at its distal end and has movable jaw parts. The jaw head has an outer thread configured to couple with an inner thread of the outer rod at its distal end. That connection provides a specific fixed rotational orientation of the jaw head relative to the outer rod. An axial movement of the attachment rod causes a closing and opening of the jaw parts.
The object of the present invention is therefore to further develop a medical instrument of the type mentioned at the outset in such a way that, while having a slender design, it is able to exert considerable forces, particularly during closure of the jaw parts, and additionally provides a high degree of freedom of the possible movements of jaw head and jaw parts relative to the shaft.